665823609 has 12 divisors (see below), whose sum is σ = 1049176752. Its totient is φ = 403529400.

The previous prime is 665823607. The next prime is 665823643. The reversal of 665823609 is 906328566.

It is a happy number.

665823609 is a `hidden beast` number, since 6 + 6 + 582 + 3 + 60 + 9 = 666.

It is not a de Polignac number, because 665823609 - 2¹ = 665823607 is a prime.

It is not an unprimeable number, because it can be changed into a prime (665823607) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 3362647 + ... + 3362844.

It is an arithmetic number, because the mean of its divisors is an integer number (87431396).

Almost surely, 2^665823609 is an apocalyptic number.

It is an amenable number.

665823609 is a deficient number, since it is larger than the sum of its proper divisors (383353143).

665823609 is a wasteful number, since it uses less digits than its factorization.

665823609 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6725508 (or 6725505 counting only the distinct ones).

The product of its (nonzero) digits is 466560, while the sum is 45.

The square root of 665823609 is about 25803.5580686075. The cubic root of 665823609 is about 873.2120700495.

The spelling of 665823609 in words is "six hundred sixty-five million, eight hundred twenty-three thousand, six hundred nine".